What is the sum of odd numbers from 18 to 123? Here we will show you step-by-step how to calculate the sum of odd numbers from 18 to 123.
Step 1) We start by finding the first (F) and last (L) odd numbers from 18 to 123. It is easy to do that by simply looking at the numbers. The first odd number is 19, and the last odd number is 123.
F = 19
L = 123
Step 2) Next, we calculate the total odd numbers (T) there are from 18 to 123, using a formula. Here is the formula and the math:
T = (L - F + 2) ÷ 2
T = (123 - 19 + 2) ÷ 2
T = 106 ÷ 2
T = 53
Step 3) Finally, we use the information from Step 1 and Step 2, and another formula, to calculate the sum of odd numbers from 18 to 123, like this:
Sum = (T ÷ 2) × (2 × F + (2 × (T - 1))
Sum = (53 ÷ 2) × (2 × 19 + (2 × (53 - 1))
Sum = 26.5 × (38 + 104)
Sum = 26.5 × 142
Sum = 3763
Sum of odd numbers from 18 to 123 = 3763
Sum of Odd Numbers Calculator
Please use the tool below to calculate the sum of odd numbers for another set of numbers.